The field of the present disclosure relates generally to turbine engines, and more particularly to hot gas path components having trailing edge near wall cooling.
Gas turbine systems are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor, a combustor, and a turbine. During operation of the gas turbine system, various hot gas path components in the system are subjected to high temperature flows, which can cause the hot gas path components to fail. Since higher temperature flows generally result in increased performance, efficiency, and power output of the gas turbine system and are thus desired in a gas turbine system, the hot gas path components that are subjected to high temperature flows must be cooled to allow the gas turbine system to operate with flows at increased temperatures.
As the maximum local temperature of the hot gas path components approaches the melting temperature of the hot gas path components, forced air cooling becomes necessary. For this reason, airfoils of gas turbine buckets and nozzles often require complex cooling schemes in which air, typically bleed air, is forced through internal cooling passages within the airfoil, and then discharged through cooling holes or passages located at the airfoil surface, leading edge, and/or trailing edge to transfer heat from the hot gas path component.
In some known gas turbine systems, the hot gas path component cooling is achieved by locating impingement inserts within the component airfoil cavities, e.g., two or more cavities of a first stage nozzle of a gas turbine. In such known systems, the pressure and suction sides of the nozzle vane are impingement cooled. The post-impingement cooling air is then either discharged through film holes along the airfoil surface or sent to an additional circuit to convectively cool the airfoil trailing edge. Additional trailing edge circuits are often required due to insufficient space within the airfoil cavity to extend the aft impingement insert to the trailing edge.
Various strategies are known in the art for cooling the hot gas path components that are subjected to high temperature flows. For example, various trailing edge air cooling circuits use pins extending between the opposite sides of the airfoil for receiving the cooling flow for cooling the trailing edge portion. Pin cooling, however, is associated with a pressure drop and is often practical over very short distances. In some know cooling systems, turbulative convective channel designs have been used, resulting in a lower pressure drop. However, such know designs may achieve insufficient cooling efficiency to meet cooling performance requirements for the nozzle vane. Some known cooling systems combine the two cooling features, i.e., pin cooling and convective channel cooling circuits, however, there is a need for even further cooling efficiencies.